This invention relates generally to suppression of accidental fires involving cooking oil or fat, and more particularly concerns employment of pure water mist in such suppression, as well as extinction of such fires.
In recent years, the development of high-efficiency cooking equipment with high energy input rates and the widespread use of vegetable oils with high burning temperature have increased potential risks to life and property loss. Almost 50% of all accidental fires in hotels, restaurants and fast food outlets start in kitchens and the majority of these involve liquid cooking oil or fat fires. These fires are the hardest to extinguish and are easily re-ignited. Suppressing cooking oil fires has been identified as the primary fire challenge in restaurant cooking areas. Recently cooking oil fires, due to their different behavior from other types of liquid fuel fires, were re-classified into a new class of fire, Class K, by the National Fire Protection Association (NFPA); a similar classification is also being considered by the Loss Prevention Council and other agencies around the world.
Previous studies showed that foam, powder and carbon dioxide are not as effective in suppressing cooking oil fires as they are for other types of liquid fuel fires. Currently, wet chemical agents, as defined by NFPA-17A, are the primary means used to extinguish grease fires in cooking areas. They are effective in extinguishing these fires, but may cause irritation to the skin and eyes as well as clean-up problems after fire extinguishment. Furthermore, the system cost of wet chemical agents is relatively high. As a result, there is a significant need for improving fire safety and reducing the cost of protecting restaurant cooking areas through the introduction of a new effective extinguishing system.